Motor control device

ABSTRACT

In order to reduce undesired sound caused by circular ring oscillation in the diametric direction of the stator by an electromagnetic force, electromagnetic force drift memory stores a drift information of the electromagnetic force causing the circular ring oscillation of the stator. This electromagnetic force drift information is read out according to the position information θ and is supplied to a correction coefficient generating circuitry. Correction coefficient generating circuitry corrects the amplitude component of the activation current wave from by forming correction coefficient β (t) of the activation current so as to cancel the electromagnetic force harmonic component in the diametric direction which component is the component of the circular ring oscillation of the stator.

BACKGROUND OF THE INVENTION

Present invention relates to a control device of a rotating electricalmachinery and especially relates to the rotating electrical machinerywhich is improved so as to reduce electromagnetic oscillation in adiameter direction of a stator of a permanent magnet rotating electricalmachinery and undesired sound caused by the electromagnetic oscillation.Permanent magnet rotating electrical machinery usually has a stator anda rotor.

The stator has a stator core formed plural winding slots respectivelykeeping a same interval and a stator winding which is wound in thewinding slot mentioned above.

Magnetomotive force distribution of the stator winding is formed so asto superimpose a space harmonic wave on a sine wave (fundamental wave)and is varied in time in proportion to a stator winding current.

Moreover in an inner diameter side of the stator, an opening part of thewinding slot and a teeth part of the stator core are disposedalternatively keeping a same interval, and a magnetism permeancedistribution of the stator becomes to contain ripple haveing a cyclemade by the winding slot of the stator core.

Magnetic flux density of the magnetic field that the stator forms in theair gap is detemined by a product of a magnetomotive force distributionof this stator and a magnetism permeance of said stator, and thismagnetic flux density contains a space harmonic component.

Moreover, the rotor has a permanent magnet fixed by being inserted in agroove provided in the rotor core keeping certain interval.

Accordingly, a magnetic flux density of the magnetic field that therotor provides in the air gap, contains the ripple in the same way andchanges in time because of being turned.

As the magnetic flux density of the air gap is provided by composing themagnetic flux that the stator forms and the magnetic flux that the rotorforms, the magnetic flux density in this air gap is distributed so as tosuperimpose the harmonic component on the fundamental wave component,and changes in time.

Because a torque acting on the rotor is an angle differentiation of amagnetic energy saved in the air gap, a ripple occurs to a torquegenerated by the ripple of the magnetic flux density of this air gap.

This torque ripple sometimes causes a case as that a big oscillation inpermanent magnet rotating electrical machinery and an undesired soundthereby appears.

In order to reduce the ripple of the torque by controlling the statorwinding current, a phase current correction means to correct so as toincrease or decrease up to a maximum value of the sine wave within arange of +30 degree of an electrical angle where magnitude of each phasecurrent becomes maximum, and a control device of a synchronism motorprepared with a balancing means which provides a total of the phasecurrent balance are disclosed, for example, in Japanese patent Laid-openNo. 8-331884 and U.S. Pat. No. 4,240,020.

By using these means, a method how to correct decreasing of the torquein a rotational direction occured in the transposition of the phasecurrent is suggested.

As a cause of the electromagnetic undesired sound of the rotatingelectrical machinery, a circular ring oscillation of the stator may bepointed out besides the torque ripple in a rotational direction thereof.

The electromagnetic force of the diameter direction acting on the statorcauses the circular ring oscillation of this stator, and it ispropagated to a stator frame of a stator periphery so as to vibrate saidstator frame to the diameter direction and to generate the undesiredsound.

When space degree and frequency of the electromagnetic force harmoniccomponent in the diameter direction, accords to resonance mode andfrequency of the stator, the stator produces a resonance so as to occura big undesired sound. Because the torque ripple is time variation ofthe electromagnetic force in a tangent direction, the conventionalcontrol device to reduce the torque ripple in the rotation directionwhich is performed up to now, cannot reduce the undesired sound causedby the magnetic force in the diameter direction.

SUMMARY OF THE INVENTION

An object of the present invention is to reduce the oscillationgenerated by a drift of the electromagnetic force in the diameterdirection of the stator in the rotating electrical machinery.

In a control device of a rotating electrical machinery comprising, aninverter disposed between a stator winding and a direct current powersupply of said rotating electrical machinery having a rotor formed astator and the magnetic pole provided a stator winding on a stator core,an activation waveform generating circuit to occur an activation currentwave form signal that met a magnetic pole position of said rotor, and acurrent control circuit to control the inverter so as to supply saidactivation electric current to the stator winding based on saidactivation current wave form signal and a stator winding currentdetecting signal, the present invention is characterised by comprising

an electromagnetic force drift memory for memorizing a drift informationof the electromagnetic force in diameter direction of the stator to acton the stator core having a stator winding thereon, and

an activation waveform correction means to correct an amplitude of saidactivation current wave form signal based on an electromagnetic forcedrift information which is read from said electromagnetic force driftmemory according to the magnetic pole position of the rotor.

Futhermore, the present invention is characterised by comprising

an electromagnetic force drift detecting means for detecting a drift ofthe electromagnetic force in a diameter direction of the stator to acton the stator core having a stator winding thereon,

an electromagnetic force harmonic operation device to calculate anelectromagnetic force harmonic component on the basis of a signaldetected by said electromagnetic force drift detecting means,

a correction information generating circuitry to occur a correctioninformation to correct an electromagnetic force drift in the diameterdirection of the stator by reading out the electromagnetic forceharmonic component from the electromagnetic force harmonic operationdevice according to the magnetic pole position of the rotor, and

an activation waveform correction means to correct the amplitude of theactivation current wave form signal based on the correction information.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a circuitry block diagram of a control device of the permanentmagnet rotating electrical machinery as the first embodiment of thepresent invention.

FIG. 2 is a vertical sectional view of the permanent magnet rotatingelectrical machinery in the first embodiment.

FIG. 3 is a vertical sectional front elevation view of the permanentmagnet rotating electrical machinery shown to FIG. 2.

FIG. 4 is a view for showing a oscillation mode of space zero degree inthe first embodiment.

FIG. 5 is a view to show an electromagnetic force harmonic component ofthe space zero degree in the first embodiment.

FIG. 6 is a view to show time change of electromagnetic force harmoniccomponent in the first embodiment.

FIG. 7 shows a current wave form flowing through one phase of the statorwinding in the first embodiment.

FIG. 8 is a characteristic figure showing change of the electromagneticforce for adjustment variables in the first embodiment.

FIG. 9 is a frequency characteristic figure of oscillation amplitude inthe first embodiment.

FIG. 10 is a layout drawing of a search coil in the second embodiment ofthe present invention.

FIG. 11 is a view of a search coil winding in the second embodiment.

FIG. 12 is a block diagram showing a flow of signal processing in thesecond embodiment.

FIG. 13 is a circuitry block diagram of a control device of a permanentmagnet rotating electrical machinery in the second embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to the drawings, the best mode of the embodiment to enforcethe present invention will be explained as follows.

FIG. 1 is a circuitry block diagram of a control device of a permanentmagnet rotating electrical machinery in the first embodiment of thepresent invention.

FIG. 2 is a vertical section side view of the permanent magnet rotatingelectrical machinery in this embodiment, and FIG. 3 is a verticalsection from elevation of the above. In FIG. 2 and FIG. 3, reference isa permanent magnet rotating electrical machinery, 2 a rotor, 21 astator.

The rotor 2 has a rotor core 19 that is provided around a shaft 20 andpermanent magnets 18 forming a magnetic pole around the rotor core 19.on the shaft 20 furthermore, a position sensor 6 to detect magnetic poleposition of the rotor 2 and an encoder 7 to detect the rotating speedare installed.

On the other hand, stator 21 has a stator core 17, a winding slot 17 aformed in the stator core 17, a stator winding 3 wounded in this windingslot 17 a so as to generate a rotational magnetic field, and atemperature sensor 22 to detect temperature of the stator core 17.

Further, 17 b is a yoke part of the stator core 17, and 17 c is a toothpart.

A control device for controlling this permanent magnet rotatingelectrical machinery 1 will be explained using FIG. 1 in the next.

This control device prepares is provided a speed control function, andan example activated with a current wave form of a sine wave isexplained.

Most of a control system performing arithmetic processing is constitutedso as to utilize a microcomputer, and the control processing function ofthe above is indicated as a control circuit here.

An inverter 4 receives an initial power from a direct current powersupply 5, and supplies a stator winding current (activation current) toa stator winding 3 of the permanent rotating electrical machinery 1.

A position detecting circuit 14 obtains and outputs a positioninformation θ based on a magnetic pole position detecting signal of therotor 2 output from the position sensor 6 and a rotating speed detectingsignal output from the encoder 7.

The speed control circuitry (ASR) 16 inputs a velocity reference ωs anda real velocity ωf obtained by converting a position information θ fromthe position detecting circuit 14 with a F/V converter 15, calculates adifference ωe (=ωs-ωf), and outputs a mean torque reference Tav and aphase shift reference when needed need by a PI control (integralsection) on the basis of the above.

The sign wave generating circuitry 10 generates a sine wave fundamentalwave form (activation current wave form) signal Iav which is same-phasewith an induced voltage of the stator winding 3 or is shifted the phasewhen needed. Based on the position information θ output from theposition sensor 6.

The electromagnetic force drift memory 13 stores the drift informationof the electromagnetic force to cause circular ring oscillation of thestator 21.

Then, this electromagnetic force drift information begins to be readaccording to the position information θ, and it is supplied to acorrection coefficient generating circuitry 12.

The correction coefficient generating circuitry 12 generates acorrection coefficient β (t) which seems to deny a drift of theelectromagnetic force harmonic component as the main component of thecircular ring oscillation in a diameter direction of the stator 21, thatis, the amplitude component of the activation current.

Here, t shows a time, and the correction coefficient varies with thetime.

Because, as the amount of the circular ring oscillation of the stator21, is influenced by the temperature of the stator core 17, thecorrection coefficient generating circuitry 12 obtains the correctioncoefficient β (t) by adding the stator core temperature information Thdetected by the temperature sensor 22.

The multiplier 23 calculates a torque reference tmod and makes thecorrection by multiplying the correction coefficient β (t) into the meantorque reference tav generated by the speed control circuitry (ASR) 16.

The 2 phase-3 phase conversion circuitry 11 inputs the corrected torquereference Tmod and the sine wave fundamental wave form signal Iav andgenerates a current reference Isa, Isb, Isc for the activation currentto flow to the winding of each phase of the stator winding 3.

The phase current control circuit (ACR) 9 a, 9 b, 9 c which controlscurrent of each phase of the stator winding 3, controls the activationcurrent of the each phase by supplying a control signal obtainedproportional to the current reference Isa, Isb, Isc and the currentdetecting signal Ifa, Ifb, Ifc from the current detecting device 8 a, 8b, 8 c, to the inverter 4, thereby the rotational magnetic field thatmatches the rotation position of the rotor 2 is generated.

Such drift of the electromagnetic force in the permanent magnet rotatingelectrical machinery 1 will be explained referring to FIG. 4 and FIG. 5.

FIG. 4 shows an oscillation mode of the stator 21 by the electromagneticforce harmonic of the zero space degree which occurs a big undesiredsound with the lowest degree.

The oscillation mode of the zero space degree means a mode in which anode or antinode of the oscillation does not exist.

That is, in this oscillation mode, the stator 21 expands and contractsin a diameter direction uniformly. FIG. 5 shows an electromagnetic forceharmonic component of the zero space degree.

In the next, a relationship of the stator winding current and theelectromagnetic force in the diameter direction will be explained usingFIG. 6 and FIG. 7.

The value of the electromagnetic force in the diameter direction of thestator 21 can be obtained from a relative position of the rotor 2 forthe stator 21 and the value of the stator winding current.

FIG. 7 shows a current wave form in one phase of the stator winding 3.

In this embodiment, when the sine wave electric current is flowed in thestator winding 3, an electromagnetic force harmonic component of a timedegree as shown to FIG. 5 occurs with the oscillation mode shown to FIG.4.

The biggest component is the zero time degree further. However, becausethe component of zero time degree is the dc component that does notdepend to the time, it acts toward the center direction with the staticforce, accordingly, the component of the zero time degree does not makea contribution to the oscillation.

In this embodiment, the sixth and the twelfth time degrees became a maincomponent to generate the circular ring oscillation.

When the frequency of the electromagnetic force harmonic accords to theresonance frequency in the oscillation mode of stator 21, the stator 21resonates so as to produce the big oscillation and the undesired sound.

Here, an example in which the component of the twelfth time degreecxcitates the resonance, will be explained.

However, the fundamental frequency of the activation current wave formis treated as a standard of the time degree.

In FIG. 6, the electromagnetic force drift is shown in a case that DCcomponent of the electromagnetic force harmonic component (component ofthe zero time degree) and the oscillation of the electromagnetic forcein the twelfth time degree are added together by considering the phase.

This electromagnetic force drift can be expressed in the next equation(1).

F(t)=F _(0,0) +F _(0.12) sin(12ωt+α_(0,12))  (1)

Here, F 0,0 and F 0,12 respectively means amplitudes of theelectromagnetic force harmonic components respectively in the zero spacedegree and the zero time degree, and the zero space degree and thetwelfth time degree.

The code α0,12 means the phase of the electromagnetic force harmoniccomponent in the zero space degree and the twelfth time degree.

These amplitude and phase data can be obtained by an experiment or aharmonic analysis of the numerical analysis.

The activation current wave form of the stator winding 2 becomes a sinewave fundamental wave form to show it in figure

The electromagnetic force harmonic component in the zero space degreeand the zero time degree, and the zero space degree and the twelfth timedegree is varied with the activation current of the stator winding 3.

In the electromagnetic force drift shown in FIG. 6, when electromagneticexciting force is big, the torque reference is made to be small, and onthe contrary, when the electromagnetic exciting force is small, thetorque reference is made to be big, thereby, the electromagnetic forceis controlled to be constant and the oscillation and the undesired soundcan be reduced.

An example to make the electromagnetic force F 0,0 as the constant valuewill be explained.

First of all, the correction coefficient β (t) which seems to besatisfied with the next equation (2) is obtained.

β(t)F(t)=F _(0,0)  (2)

By forming current references Isa, Isb, Isc which transformes the sinewave fundamental wave form (signal Iav) with the correction coefficientβ (t), the amplitude of the activation current is controlled as awaveform which is corrected as shown in FIG. 7, thereby, the drift ofthe electromagnetic force in the diameter direction of stator by timedegree the twelfth component is suppressed, and the electromagneticforce may be kept to be F 0,0.

Here, the correction coefficient β (t) can be expressed in the nextequation (3). $\begin{matrix}\begin{matrix}{{\beta (t)} = \frac{F_{0,0}}{F_{0,0} + {F_{0,12}{\sin \left( {{12\omega \quad t} + \alpha_{1,12}} \right)}}}} \\{= \frac{1}{1 + {\frac{F_{0,12}}{F_{0,0}}{\sin \left( {{12\omega \quad t} + \alpha_{0,12}} \right)}}}}\end{matrix} & (3)\end{matrix}$

Here, because F 0,12 is fully small comparing it with F 0,0 and a nextequation (4) is provided. $\begin{matrix}{{\beta (t)} = {1 - {\frac{F_{0,12}}{F_{0,0}}{\sin \left( {{12\omega \quad t} + \alpha_{0,12}} \right)}}}} & (4)\end{matrix}$

Practically, because of an affection of a magnetic saturation of thecore of the stator 21 and the rotor 2, the equation (4) is not correctedenough.

Therefore, it is desirable to use an adjustment variables γ which arevariables considering affection of the magnetic saturation further tothe correction coefficient β (t).

Then the correction coefficient β (t) may be expressed in the followingequation (5). $\begin{matrix}{{\beta (t)} = {1 - {\gamma \frac{F_{0,12}}{F_{0,0}}{\sin \left( {{12\omega \quad t} + \alpha_{0,12}} \right)}}}} & (5)\end{matrix}$

By using the adjustment variables γ as a parameter, the electromagneticforce harmonic component of the twelfth degree mentioned above iscalculated, and the variation of the electromagnetic force harmoniccomponent for this adjustment variables γ is shown in FIG. 8.

When the adjustment variables Y are zero, a condition as that anycorrectionis not made on at all is shown.

In this embodiment, the case of γ=4 can reduces a ratio of theelectromagnetic force to be 1% in comparison with the case of γ=0(100%).

Accordingly, the oscillation and the undesired sound to originate inthis electromagnetic force harmonic component becomes possible to bereduced largely.

In an electromagnetic force drift memory 13, a resonance frequency to beprovided by an electromagnetic analysis or an experiment, theelectromagnetic force harmonic component which should be reduced, thetime degree, the amplitude, and the phase of the harmonic component ofthe current, and the adjustment variables, are stored by a form such asa table etc.

In the permanent magnet rotating electrical machinery which is preparedwith a stator winding of n phase, the harmonic component of theelectromagnetic force has periodicity of 180/n degree in electricalangle.

Accordingly, if the data of the electromagnetic force harmonic arestored relating to a current-carrying section of 180/n degree in theelectrical angle, they are read out repeatedly and are used to correctit in all sections.

According to the present embodiment, it has an effect as that theoscillation by the circular ring oscillation of the stator 21 and theundesired sound thereby may be reduced.

Moreover, the embodiment using the twelfth time degree is described asabove, however, the oscillation and undesired sound in other timedegrees, can be reduced in the same way.

Moreover, the correction coefficient β (t) is multiplyed with a meantorque reference value Tav by a multiplier 23 so as to correct theamplitude component of the activation current, thereby to obtain acorrected torque reference Tmod, however, the corrected torque referenceTmod may be obtain by adding the correction component being equivalentto the multiplication to the mean torque reference value Tav.

Moreover, in FIG. 1, the correction signal from the correctioncoefficient generating circuitry 12 is added to the mean torquereference Tav so that the amplitude component of the activation currentis corrected indirectly. However, the correction signal from thiscorrection coefficient generating circuitry 12 may be added directly toa two phase-three phase conversion circuitry 11, thereby the activationcurrent is corrected a shown in FIG. 7.

As an example applied this embodiment next, a case applied to a variablespeed motor will be explained.

FIG. 9 exemplifies a frequency characteristic of the oscillationamplitude.

In this example, plural resonance frequencies f1, f2 exist in the motor.

When a revolutional speed of the motor is changed and the frequency ofthe electromagnetic force harmonic component becomes to be close to theresonance frequency f1, f2, the correction function means mentionedabove is operated, and when it is driven with an other frequency domain,the correction function means is stopped.

If it is done in this way, in the variable speed motor, the oscillationand the undesired sound can be reduced in the resonance frequency;furthermore processing load of the control system is reduced by omittingcontrol to correct the electromagnetic force drift in the non-resonanceregion, it becomes possible to to utilize redundant throughput for othercontrol processings.

In next, as a second embodiment of the present invention, an example ofa permanent magnet rotating electrical machinery of three phase fourpole will be explained.

FIG. 10 shows a vertical sectional front view of the stator core of thethree phase four pole permanent magnet rotating electrical machinery.

In this embodiment, slot number n spp of the stator core 17 per everypole every phase of the stator 21, is “4”. Phase belt of the statorwinding 3 of three phase is 60 degree in the electrical angle.

The winding slot number in this phase belt is equal to n spp and it isfour.

Moreover, as mentioned above, the harmonic component of theelectromagnetic force has a periodicity of 180/n degree in theelectrical angle.

That is, the periodicity arises in every phase belt. Accordingly, if thesearch coils 30 a to 30 d are provided on four stator winding slot inone phase belt, the harmonic component of the electromagnetic forcenecessary for the correction control processing can be grasped by asufficient accuracy.

Each search coil 30 (30 a to 30 d) is wound more than one turn so as tosurround a teeth part 17 c as shown in FIG. 11.

FIG. 12 shows a step for the signal processing to calculate theelectromagnetic force based on a variation of the magnetic fluxinterlinkaged with the teeth part 17 c.

Moreover, a circuitry block of the control device corresponding to thissignal processing is shown to FIG. 13.

Relating to the permanent magnet rotating electrical machinery and thecontrol device thereof shown to FIG. 13, an equal or equivalentcomponent part with the embodiment shown in FIG. 1, is omitted to bedescribed repeatly by attaching the same reference code.

Referring to the rotation position information signal θ and by using asignal of one set point as a trigger, an induced voltage of the searchcoil 30 a to 30 d of each tooth part 17 c is measured.

Because this induced voltage is in proportion to a time variation of themagnetic flux which interlinkages to each teeth part 17 c, the magneticflux density can be obtained by integrating this induced voltage signalwith the time. This integral can be obtained based on digital quantityor may be used an integrating circuit.

Because the electromagnetic force in the diameter direction of thestator is in proportion to square of the magnetic flux densityapproximately in the diameter direction, the electromagnetic force canbe calculated by operating the magnetic flux density signal into square.

Electromagnetic force data of each tooth part 17 c are developed betweenspace, and the harmonic component of the electromagnetic force iscalculated by performing an electromagnetic force harmonic operationfurthermore.

The harmonic component of the electromagnetic force that the resonancemode and the frequency accord with a dc component is extracted.

This signal processing is performed in an electromagnetic forceoperating unit 40 shown in FIG. 13.

Based on this operation result, the correction coefficient β (t) isgenerated from the correction coefficient generating circuitry 12, andthe amplitude component of the activation current wave form in thestator winding 3 is corrected by means for multiplying it to the sinewave fundamental wave form.

Further, in this embodiment, an element for detecting a mechanical driftcan be used as an electromagnetic force drift detecting means.

An acceleration sensor for detecting the oscillation around the statorcore or a microphone for measuring the undesired sound is provided,thereby it becomes possible to take out the harmonic component of theelectromagnetic force so as to process it, by a processing techniquesame as the electromagnetic signal processing as mentioned above.

According to this embodiment, because the electromagnetic force harmoniccomponent can be calculated correcponding to aged deterioration of theelectric motor and the load machine, there is an effect to reduce theoscillation and the undesired sound furthermore.

According to the present invention as stated above, there is aremarkable effect as that the oscillation of the diameter directiongenerated by the electromagnetic force of the rotating electricalmachinery can be reduced, and the undesired sound to originate in thisoscillation is reduced.

What is claimed is:
 1. A control device for a rotating electricalmachinery having a stator with a stator winding for a stator core and arotor with a magnetic pole having a plurality of permanent magnetsformed thereon, comprising an inverter operatively connected with saidstator winding and a direct current power supply, activation waveformgenerating circuitry for generating an activation current wave formsignal corresponding to a magnetic pole position of said rotor, andcurrent control circuitry for controlling said inverter so as to flow anactivation current into said stator winding based on said activationcurrent wave form signal and a detecting signal to detect a currentflown in said stator winding, an electromagnetic force drift memory forstoring drift information of said electromagnetic force in a diametricdirection of said stator acting on said stator core having said statorwinding, and an activation waveform correction means for correcting anamplitude of said activation current wave form signal based onelectromagnetic force drift information read from said electromagneticforce drift memory according to said magnetic pole position of saidrotor.
 2. A control device for a rotating electrical machinery having astator with a stator winding for a stator core and a rotor with amagnetic pole having a plurality of permanent magnets formed thereon,comprising an inverter operatively connected with said stator windingand a direct current power supply, activation waveform generatingcircuitry for generating an activation current wave form signalcorresponding to a magnetic pole position of said rotor, and currentcontrol circuitry for controlling said inverter so as to flow anactivation current into said stator winding based on said activationcurrent wave form signal and a detecting signal to detect a currentflown in said stator winding, an electromagnetic force drift detectingmeans for detecting a drift of the electromagnetic force in a diametricdirection of the stator to act on the stator core having a statorwinding there, an electromagnetic force harmonic operation device tocalculate an electromagnetic force harmonic component on the basis of asignal detected by said electromagnetic force drift detecting means,correction information generating circuitry to provide a correctioninformation to correct an electromagnetic force drift in the diameterdirection of the stator by reading out the electromagnetic forceharmonic component from the electromagnetic force harmonic operationdevice according to the magnetic pole position of the rotor, andactivation waveform correction means to correct the amplitude of theactivation current wave form signal based on the correction information.3. A control device for a rotating electrical machinery as defined inclaim 1, wherein said activation current wave form is a sine wave.
 4. Acontrol device for a rotating electrical machinery as defined in claim1, wherein a space degree of harmonic component of said electromagneticforce is zero.
 5. A control device for a rotating electrical machineryas defined in claim 1, wherein said rotating electrical machinery has astator winding of n phase, and a section to store an harmonic componentof said electromagnetic force is 180 degree/n in electrical angle.
 6. Acontrol device for a rotating electrical machinery as defined in claim2, wherein said electromagnetic force drift detecting means is one of anelectric signal detection element, an oscillation detecting element andan undesired sound measurement element.
 7. A control device for arotating electrical machinery as defined in claim 1, wherein correctionof said activation current wave form is performed by limiting within aresonance region.
 8. A control device for a rotating electricalmachinery as defined in claim 1, wherein means is provided to change acorrection characteristic of said activation current wave form accordingto a temperature of said rotating electrical machinery.